1. Technical Field
The present invention relates generally to restricting access to electronic documents, and more particularly to restricting access to desired information subsets of electronic documents.
2. Discussion of Related Art
A content management system is a system that can typically manage all types of electronic documents including, for example, HTML and XML Web content, document images, office documents, e-mail messages, textual data, printed output, audio, video, and other digital representations of information. A conventional content management system provides security in the form of access control settings or permissions, whereby the extent of users' access to various resources is set forth. For example, in a company, certain users may have read only privileges for a particular electronic document, other users may have read/write privileges, while still other users may have no access privileges at all. These access control settings are usually tracked by means of an access control list, which is a data structure such as a table that specifies the rights of a user or group of users to access specific electronic documents.
Access control lists can restrict and provide a basic level of security, but may not provide the degree of access granularity desired to specific electronic documents of interest. For example, it may be desirable to limit access to certain sensitive documents or parts thereof, but not desirable to entirely disable or block access to the documents or hide their existence. Accordingly, individuals, organizations, associations and other types of entities interested in controlling access to electronic documents have a continuing interest in developing more flexible access control technologies that provide a greater degree of access granularity.